Jammed sheet reverse using active retard feeder

ABSTRACT

A fully active retard feeder is configured to move a partially feed sheet back into a feed tray in response to a jam either in the nip of the feed head or in a location downstream of the feed head and thereby ease user jam clearance.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to a printing apparatus that includes a friction retard feeder, and more particularly, to an improved jam clearance system for use in such feeders.

2. Description of Related Art

When a sheet is jammed in a downstream location in the paper path of a printer it is more than likely that a sheet will be left partially fed in the feed nip of the input media feeder of virgin sheets into the printer. Presently, this sheet is manually cleared by the user, but it is very likely that it will be damaged during this process and possibly leading to an unclearable jam, and therefore, to an unscheduled maintenance call. Also, when there is a multiple sheet jam in the feed head of the media feeder itself due to, for example, a misfeed the user must manually clear the jam, however, some parts of the sheets may be in a location that is unclearable which could lead to an unscheduled maintenance call to a repairman.

Heretofore, various jam clearing methods have been employed. For example, U.S. Patent Publication No. 20080079210 A1 shows a marking machine that includes a system that automatically clears itself of jams in the machine when the machine is unattended. The paper transport is enabled to move forward and backward and when a jam occurs it will automatically move backward until the jam is cleared. In U.S. Pat. No. 4,231,567 a method and apparatus for clearing jams in the transport path of a copier includes the steps of sensing a jam, clustering in process sheets at the jam or at a location upstream of the jam location, while simultaneously allowing the sheet downstream of the jam location to continue. In U.S. Pat. No. 6,010,127 a buckle chamber is provided along a sheet path where jammed sheets are compiled during a down cycle during a jam.

Unfortunately, even though the jam clearance techniques of the above prior art are useful, the jam clearance problems of virgin sheet input feeders mentioned-hereinabove are still present.

BRIEF SUMMARY

In answer thereto, provided hereinafter is a fully active retard feeder that feeds sheets from a stack and adapted in response to a jam in feed head of the retard feeder or downstream jam to move a partially feed sheet in a reverse direction back into the stack.

The disclosed system may be operated by and controlled by appropriate operation of conventional control systems. It is well known and preferable to program and execute imaging, printing, paper handling, and other control functions and logic with software instructions for conventional or general purpose microprocessors, as taught by numerous prior patents and commercial products. Such programming or software may, of course, vary depending on the particular functions, software type, and microprocessor or other computer system utilized, but will be available to, or readily programmable without undue experimentation from, functional descriptions, such as, those provided herein, and/or prior knowledge of functions which are conventional, together with general knowledge in the software of computer arts. Alternatively, any disclosed control system or method may be implemented partially or fully in hardware, using standard logic circuits or single chip VLSI designs.

The term ‘sheet’ herein refers to any flimsy physical sheet or paper, plastic, media, or other useable physical substrate for printing images thereon, whether precut or initially web fed.

As to specific components of the subject apparatus or methods, it will be appreciated that, as normally the case, some such components are known per se’ in other apparatus or applications, which may be additionally or alternatively used herein, including those from art cited herein. The cited references, and their references, are incorporated by reference herein where appropriate for teachings of additional or alternative details, features, and/or technical background. What is well known to those skilled in the art need not be described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Various of the above-mentioned and further features and advantages will be apparent to those skilled in the art from the specific apparatus and its operation or methods described in the example(s) below, and the claims. Thus, they will be better understood from this description of these specific embodiment(s), including the drawing figures (which are approximately to scale) wherein:

FIG. 1A is a partial, profile view of an improved fully active retard feeding system in accordance with one aspect of the present disclosure;

FIG. 1B is a partial, profile view of the improved retard feeding system of FIG. 1B showing a nudger roll in a raised position in response to a downstream jam in accordance with the present disclosure;

FIGS. 2A and 2B are flow charts showing the process used to move sheets that remain in the feed head after a jam back into the feed tray.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

While the disclosure will be described hereinafter in connection with a preferred embodiment thereof, it will be understood that limiting the disclosure to that embodiment is not intended. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.

The disclosure will now be described by reference to preferred fully active retard feed system embodiments that include an apparatus for returning sheets to a feed tray in response to a jam.

For a general understanding of the features of the disclosure, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to identify identical elements.

In the following description, the term sheet “media”, “sheet”, “print media”, or “sheet media” is used herein to refer to physical sheets of paper, plastic, cardboard, or other suitable physical substrates that can be employed for printing, whether precut or initially web fed and subsequently cut.

A media transport system in an image-forming device employs one or more sets of rollers for reliably driving a sheet along a media transport path. The present disclosure describes a roll system including a preferably non-liftable nudger roll positioned above a stack of sheets, however, if desired, the nudger roll could be moveable between positions in contact with the top sheet and raised out of such contact. A feed roll and a retard roll are mutually loaded to form a feed nip, positioned at the start of a media transport path. A drive motor powers the nudger roll and the feed roll in a feed direction (rotating to propel media sheets downstream on the media transport path). The drive motor is coupled to the nudger roll and feed roll through a feed clutch. The retard roll includes a slip clutch, driven in a reverse direction (opposite the feed direction), having a breakaway torque chosen below the torque imposed by a media sheet being fed through the feed nip. In the normal operation, the drive motor, operating through the feed clutch, drives the feed roll and the nudger roll in a feed direction, and the nudger roll picks the top sheet off the stack and propels it into the feed nip. The sheet imposes sufficient torque on the retard roll to cause the retard roll to slip on the slip clutch to rotate in the feed direction. Thus, the forward rotation of the retard roll, feed roll, and the nudger roll drives the sheet in a forward direction.

If a jam occurs elsewhere along the media transport path, all rolls are stopped, and that action often leaves a sheet partially fed through the feed nip. To deal with that situation, the system disengages the feed clutch. The drive motor continues to run and rotate the retard roll in a reverse direction. Here, no torque is imposed on the retard roll, as the feed roll is stationary, and therefore the slip clutch drives the retard roll in a reverse direction, driving the media sheet back onto the stack.

FIG. 1A illustrates a media transport system 100 configured for normal operation, feeding sheets in an image forming device (not shown). The system includes a nudger roll 124, a feed roll 104, and a retard roll 114, all mounted in the vicinity of a sheet stack 102 positioned in holder or tray 132, oriented transversely to the media transport path 134. Nudger roll 124 is positioned over the stack in FIG. 1A. Alternatively, nudger roll 124 could be vertically movable between a position in contact with the top sheet 103, as shown in FIG. 1A, to a raised position out of contact with the top sheet 103, as shown in FIG. 1B. Feed roll 104 and retard roll 114 are mutually loaded to form a feed nip 105. Feed roll 104 is carried on a feed roll shaft 106, and nudger roll 124 is carried on a nudger roll shaft 126, and a drive motor 115 drives both the nudger roll 124 and feed roll 104 in a feed direction that drives the media sheet downstream along the media transport path 134. The drive motor is coupled to these rolls through a feed clutch 108, which may be integral to the two rolls or mounted separately, as may be found convenient by those of skill in the art. Design and implementation of the feed clutch will be clearly within the skill of those in the art.

Retard roll 114 is carried on a slip clutch 118, which in turn is carried on retard roll shaft 116. The drive motor drives slip clutch in a reverse direction, opposite the feed direction, and both the retard clutch and retard roll rotate on retard roll shaft 116. The slip clutch 118 engages the retard roll 114 to drive it in the reverse direction, but at a predetermined breakaway torque, the slip clutch disengages, allowing the retard roll to turn freely. The predetermined breakaway torque is chosen to be below the toque imposed on the retard roll by a media sheet but above a value explained below.

FIG. 1A depicts a feeding state of the media transport system 100. There, the nudger roll 124 lies atop the stack 102, engaging the topmost sheet and driving it towards the feed nip 105, and toward the media transport path 134. Feed clutch 108 drives the feed roll 104 and nudger roll 124 in the feed direction, and the feed roll 104 lies in contact with retard roll 114. The drive motor also powers slip clutch 118, but in a reverse direction. Because the feed roll 104 is powered in the feed direction, however, that roll imposes a torque on the retard roll 114 that exceeds the breakaway torque; thus, retard roll 114 slips on the slip clutch 118 and rotates in the feed direction, driven by the feed roll 104. The normal operation of the feed system proceeds, with nudger roll 124 driving the top sheet 103 to the feed nip 105, where the drive roll engages the sheet and drives it in feed direction, along the media transport path 134.

When the media transport system 100 operates in normal feeding state, as noted above, the drive motor 115, being powered and coupled to the feed roll shaft 106, rotates the feed roll shaft 106 with the rotation speed of the drive motor. The feed clutch 108, being engaged to the feed roll shaft 106 and the feed roll 104, moves the sheet along the media transport path 134. On such engagements, the feed roll shaft 106 transfers the driving torque to the feed roll 104, thus rotating the feed roll 104 in the feed direction. The rotating feed roll 104 thus propels the sheet through the feed nip 105 along the media transport path 134.

When the media transport system 100 detects a jam at some point downstream from the feed nip 105, the imaging device's control system senses a jam condition and stops nudger roll 124 and feed roll 104 by disengaging feed clutch 108. That situation often leaves a single sheet 103 partially fed through the feed nip 105. The drive motor continues to operate, however, and the control system does not disengage slip clutch 118. In this situation, feed roll 104 freewheels, imposing no work on retard roll 114. Thus, the slip clutch 118 drives retard roll 114 in a reverse direction, returning sheet 103 to the top of the stack 102. This same procedure is followed if there is a jam in the feed nip 105. Also, if there is a misfeed or a jam in the feed head, any partially feed sheet caught in the feed nip 105 is reversed back into tray 132.

This reversal of functionalities enables the media transport system 100 to resets itself through the described clear jam state and return the image-forming device to a normal functional state without any human intervention.

The fault recovery process 300 shown in the flow charts of FIGS. 2A and 2B is used by the fully active retard feeder 100 to clear jams or misfeeds occurring at either the feed head of the retard feeder or downstream of the retard feeder in, for example, high capacity feed (HCF) trays 3 or 4 of a printer to move a sheet or sheets that remain in the feed head back into the tray. The fault recovery process of block 305 starts with decision block 310 that determines which tray is feeding. If tray 3 is feeding, any internal fault is monitored at block 312. If there is a fault, the particular fault is determined in block 314. If the determination is that the lead edge of the first sheet feed from tray 3 is late as shown in block 316, the HCF transport motor (not shown) drives the internal take away rolls (not shown) that are downstream of feed roll 104 for 1000 ms and ends at block 370. If the fault determination in block 314 is that the lead edge of the sheet being fed is late to a horizontal sensor as shown in block 318, a feed motor in block 326 drives the internal take away rolls for 1000 ms. If the sensor goes clear the feed motor is stopped in block 328 and the process ended at block 370. With the lead edge of the sheet being fed is late to the HCF exit sensor in block 320, the HCF transport motor performs an internal take away roll run time of 1000 ms and is ended in block 370.

Alternatively, if tray 4 is feeding, any internal fault is monitored at block 350. If there is a fault it is determined in block 352. If the determination is that the lead edge of the first sheet feed from tray 4 is late as shown in block 356, feed motor 115 is turned ON for 1000 ms. If the feed sensor in block 362 goes clear, the feed motor is stopped and the clutch is disengaged and the process ended at block 370. However, if the fault determination in block 352 is that the lead edge of the sheet being fed is late to the HCF exit sensor as shown in block 354, the HCF transport motor is actuated to run the take away rolls for 1000 ms as indicated in block 358 and ended in block 370.

As shown in block 364, the events taking place in blocks 326 and 360 will turn the feed motor ON. The clutch is not engaged so only the retard roll is running which will move the sheet back into the tray.

In recapitulation, a process and apparatus is disclosed for running a fully active friction retard feeder with the drive roll clutch disengaged for a period of time after a jam occurs to drive any sheets stopped in the feed nip back into the tray. This will prevent those sheets from being torn if the tray is pulled out as part of the jam clearance process. As a result, the incidence of torn media during jam clearance is reduced, customer satisfaction is improved and occasional unscheduled maintenance is prevented due to pieces of media being left in awkward places.

The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material. 

What is claimed is:
 1. A media transport jam clearance system for engaging a media sheet fed from a stack of media sheets and returning the engaged sheet to the media stack, the system comprising: a feed roll, carried on a feed roll shaft adjacent the stack; a retard roll, carried on a retard roll shaft, the retard roll being loaded against the feed roll to create a feed nip lying in a media transport path; a nudger roll, carried on a nudger roll shaft positioned above the media stack; a drive motor operatively coupled to the drive roll shaft, retard roll shaft and the nudger roll shaft; a feed clutch engageably coupling the feed roll shaft to drive the feed roll shaft in a feed direction to propel media sheets from the media stack to the media transport path; a slip clutch engageably coupling the retard roll shaft to drive the retard roll shaft in a direction opposite the feed direction, the slip clutch breakaway torque being below the torque imposed by the media sheet; and wherein, in a clear jam state, the feed clutch is disengaged from the feed roll shaft and the nudger roll shaft, and the slip clutch is engaged to the retard roll shaft to rotate the retard roll and drive the sheet in the direction opposite the feed direction.
 2. The media transport jam clearance system of claim 1, operable in a multiple sheet jam state, wherein, in the multiple sheet jam state, when the media transport jam clearance system engages two or more sheets, the slip clutch breakaway torque being more than the load imposed by two or more media sheets, the feed clutch is disengaged from the feed roll shaft and the slip clutch is engaged to the retard roll shaft to rotate the retard roll and drive the sheets in the direction opposite the feed direction.
 3. The media transport jam clearance system of claim 1, wherein said nudger roll is configured to move between a raised position out of contact with the media stack and a nudging position in contact with the topmost sheet in the media stack.
 4. (canceled)
 5. (canceled)
 6. The media transport jam clearance system of claim 3, wherein the feed clutch engageably couples the nudger roll shaft.
 7. The media transport jam clearance system of claim 6, wherein, in the clear jam state, the feed clutch is disengaged from the nudger roll shaft.
 8. The media transport jam clearance system of claim 6, operable in a multiple sheet jam state, wherein, in the multiple sheet jam state, the feed clutch is engaged to the nudger roll shaft.
 9. (canceled)
 10. A method for transporting media in a media transport path in a clear jam state, comprising: providing a media transport jam clearance system for engaging a single media sheet partially fed from a stack of media sheets and returning the engaged partially fed single media sheet to the media stack in response to a downstream jam in said media transport path, said media transport clearance system including: a feed roll carried on a feed roll shaft adjacent said stack; a retard roll carried on a retard roll shaft, said retard roll being loaded against said feed roll to create a feed nip lying in said media transport path; a feed clutch engagably coupling said feed roll shaft to drive said feed roll shaft in a feed direction to propel media sheets from said media stack to said media transport path; and a slip clutch engageably coupling said retard roll shaft to drive said retard roll shaft in a direction opposite said feed direction, the slip clutch having a breakaway torque being below the load imposed by said media sheet; disengaging said feed clutch from said feed roll shaft; and engaging said slip clutch to said retard roll shaft to rotate said retard roll and drive said single media sheet in the direction opposite the feed direction.
 11. The method of claim 10 for transporting media in a multiple sheet jam state, wherein, in said multiple sheet jam state, when said media transport jam clearance system engages two or more media sheets, said slip clutch breakaway torque being more than the load imposed by two or more media sheets, the method further comprising: engaging said feed clutch to said feed roll shaft; and engaging said slip clutch to said retard roll shaft to rotate said retard roll and drive said media sheet in the direction opposite the feed direction.
 12. The method of claim 10, wherein the media transport jam clearance system further includes a nudger roll, carried on a nudger roll shaft positioned above said media stack and configured to move between a raised position out of contact with said media stack and a nudging position in contact with the topmost sheet in said media stack.
 13. The method of claim 12, wherein the media transport jam clearance system further includes a drive motor operatively coupled to said nudger roll shaft.
 14. The method of claim 12, further comprising raising said nudger roll out of contact with said media stack.
 15. The method of claim 12, wherein said feed clutch engageably couples said nudger roll shaft.
 16. The method of claim 15, further comprising disengaging said feed clutch from said nudger roll shaft.
 17. The method of claim 15 for transporting media in a multiple sheet jam state, wherein, in said multiple sheet jam state, the method further comprising engaging said feed clutch to said nudger roll shaft.
 18. The method of claim 10, including feeding a partially fed single sheet caught between said feed roll and retard roll back into said stack in response to a misfeed.
 19. The media transport jam clearance system of claim 1, wherein said feed roll is adapted to freewheel when a jam is detected within a nip formed between said feed roll and retard roll.
 20. The media transport jam clearance system of claim 1, wherein said feed roll is adapted to freewheel when a jam is detected downstream of said media stack. 